Amphibious travel presents unique challenges due to the dual nature of traveling over both land and water. For example, some attributes of the craft that are an advantage on land become a disadvantage on water, and vice versa. Prior art reveals how this dilemma has been handled previously with respect to amphibious bicycle floatation systems in general, and specifically with the ability to raise and lower the floatation devices.
The height, or elevation, of the floatation devices attached to a bicycle for amphibious travel, relative to the bicycle and the ground, impact its performance and the rider's comfort on land and water. While on water it is desirable to have the floatation devices below the bicycle wheels and pedals in order to lift the bicycle and rider sufficiently above the water to keep the bicycle and rider dry. Alternatively, on land, the opposite is desirable, to have the floatation devices and related support frame sufficiently above the bottom of the bicycle wheels, that is, as high above ground level as practical, to provide ample clearance for land obstructions over varied terrain.
Previously, amphibious bicycle floatation devices can be categorized into two general groups, those with floatation devices that are fixed in place, and those that employ a lift system for raising and lowering the floats. Generally those that do not employ a lift system fix the floats at the midpoint between the two optimum elevations for traveling over both land and water. This is not ideal, but rather an accommodation to make the craft amphibious. Those with a lift system have the ability to raise and lower the floats for better clearance over both land and water.
Among the examples of amphibious bicycle devices lacking the ability to raise and lower the floatation devices is U.S. Pat. No. 4,092,945, issued to Ankert (1978), which reveals an amphibious float attachment system for a conventional bicycle. Though it is amphibious, its limitations are immediately apparent since, without a lift system, the bicycle and rider remain partially submerged in the water during water travel, and the pontoon floats appear to have little ground clearance when on land. Also, the paddles attached to each pedal for propulsion would be very inadequate for meaningful water travel. U.S. Pat. No. 4,789,365, issued to Jones (1988), shows an alternative method of fixing an amphibious float system to a conventional bicycle. The float system cannot be raised or lowered, similar to the previous example, but the structure is arranged such that the bicycle and rider sit on top of the entire system. This keeps the bicycle and rider out of the water. However, it creates the undesirable option of having to remove the entire device from the bicycle in order to use the bicycle to travel on land. This takes time and effort, and likely tools. Also, once the floatation device has been removed there is no provision to transport it with the bicycle in the likely event that another conversion to water mode will be desired later. So the rider is stuck without the ability to cross more than one body of water over the entire ride, making it a non-amphibious system for practical purposes. U.S. Pat. No. 5,807,148, issued to Siviero (1998) solves the portability issue in one respect by making the entire float and frame system able to be stowed in a back-pack to be carried by the rider. It is also adaptable to a conventional bicycle. While this theoretically solves the issue of crossing multiple bodies of water on a single trip, the practicality of stopping, assembling or disassembling the frame system and inflating the pontoons, before every transition between land and water would be very time consuming and limiting. Because of the time and effort required to temporarily convert between land and water use, the previous two examples are not amphibious in their immediate form, and are therefore not practical for everyday recreation, sport, or travel where outings are likely short and multiple consecutive land and water crossings may be desired.
Among the examples of amphibious cycles having the ability to raise and lower their floatation devices is U.S. Pat. No. 6,050,864, issued to Perdue (2000), which demonstrates amphibious floats attached to a conventional bicycle having floats that fold up and down in a sideways motion. The floats must be uncoupled from each other and then folded individually to raise the floats, and water and land clearance issues exist as it appears portions of the bicycle and likely the rider's feet contact the water, similar to previously discussed systems where the floatation devices did not lift at all. U.S. Pat. No. 3,987,747 (Locher, 1976); U.S. Pat. No. 1,034,278 (Munsen, 1912); and U.S. Pat. No. 799,667 (Payette, 1905) show amphibious floatation systems that lift longitudinally in various ways and combinations, but they are cumbersome, complicated, and do not lift all of the needed floatation devices simultaneously and in the same direction for efficient conversion between land and water travel.